This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Various abbreviations that may appear in the specification and/or in the drawing figures are defined as follows:                3GPP third generation partnership project        ACK acknowledgment        BS base station        BW bandwidth        CDM code division multiplexing        CM cubic metric        CQI channel quality indicator        DFT-S discrete Fourier transform-synchronous        DL downlink        DRS demodulation reference signal (or DM RS)        DRX discontinuous receptions        DTX discontinuous transmission        eNB evolved Node B        EUTRAN evolved UTRAN        FDD frequency division duplex        FDM frequency division multiplexing        FDMA frequency division multiple access        FH frequency hopping        HARQ hybrid automatic repeat request        IFDMA interleaved frequency division multiple access        ITU international telecommunication union        ITU-R ITU radiocommunication sector        LA local area        LTE long term evolution        NACK negative ACK (or NAK)        Node B base station        OFDMA orthogonal FDMA        PAR peak to average ratio        PDCCH physical downlink control channel        PDSCH physical downlink shared channel        PUCCH physical uplink control channel        PUSCH physical uplink shared channel        QAM quadrature amplitude modulation        QPSK quadrature phase-shift keying        RACH random access channel        RB radio band        Rel. 8 3GPP Release 8        Rel. 9 3GPP Release 9        RF radio frequency        RPF repetition factor        RRC radio resource control        RS reference signal        SC single carrier        SINR signal to interference-plus-noise ratio        SNR signal-to-noise ratio        SRI scheduling request indicator        SRS sounding reference signal        TDD time division duplex        TDM time division multiplexing        TTI transmission time internal        UE user equipment        UL uplink        UMTS universal mobile telecommunications system        UpPTS uplink pilot timeslot        UTRA UMTS terrestrial radio access        UTRAN UMTS terrestrial radio access network        WA wide area        
A proposed communication system known as evolved UTRAN (EUTRAN, also referred to as UTRAN-LTE or as E-UTRA) is currently under development within the 3GPP. As currently specified the DL access technique is OFDMA, and the UL access technique is SC-FDMA.
One specification of interest to these and other issues related to the invention is 3GPP TS 36.300, V8.3.0 (2007, December), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Access Network (E-UTRAN); Overall description; Stage 2 (Release 8).
Of particular interest herein is, for example, subclause 5.2.3, “Physical uplink control channel”, which states that the PUCCH is mapped to a control channel resource in the uplink. A control channel resource is defined by a code channel and two resource blocks, consecutive in time, with frequency hopping at the slot boundary. Depending on the presence or absence of uplink timing synchronization, the uplink physical control signaling can differ. In the case of time synchronization being present the control signaling consists of CQI, ACK/NAK and scheduling request indicator (SRI). The CQI informs the scheduler about the current channel conditions as seen by the UE. If multiple-input and multiple-output (MIMO) transmission is used, the CQI includes necessary MIMO-related feedback. The HARQ feedback in response to downlink data transmission consists of a single ACK/NACK bit per HARQ process. The PUCCH resources for SRI and CQI reporting are assigned and can be revoked through RRC signaling. A SRI is not necessarily assigned to UEs acquiring synchronization through the RACH (i.e., synchronized UEs may or may not have a dedicated SRI channel). PUCCH resources for SRI and CQI are lost when the UE is no longer synchronized.
Reference can also be made to 3GPP TR 36.211, V1.0.0 (2007, March), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Physical Channels and Modulation (Release 8), for a description in Section 5 of the UL physical channels, including the PUSCH (Section 5.3), the PUCCH (Section 5.4), and the reference signals DM RS (associated with transmission of the PUSCH or PUCCH) and SRS (not associated with transmission of the PUSCH or PUCCH) in Section 5.5.
Recently proposed have been enhancements to the Rel. 8 (LTE) system, which may be referred to as Rel. 9 or as LTE-Advanced (LTE-A). Backward compatibility of LTE and its further releases is being emphasized. It has been decided that LTE Rel. 8 terminals should be able to operate in the LTE-A system. Furthermore, it has been decided that LTE-A terminals should be able to operate in LTE Rel. 8 system. The LTE-A system may provide a significantly wider bandwidth (e.g., 100 MHz) made up of, for example, five channel bonded 20 MHz carriers.
Reference with regard to LTE-A may be made to 3GPP TSG RAN WG1 Meeting #53, Kansas City, USA, May 5-9, 2008, R1-081948, Proposals for LTE-Advanced Technologies, NTT DoCoMo, Inc.
Reference can also be made to 3GPP TR 36.913, V0.0.6 (2008, May), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Requirements for Further Advancements for E-UTRA (LTE-Advanced) (Release X).
There is an increasing focus on extending and optimizing 3GPP radio access technologies for Local Area (LA) access solutions in order to provide new services with high data rates and with low cost.
One problem to be addressed is how to best arrange/optimize UL control channel transmission in the LTE-A FDD/TDD system, as there are differences between Rel. 8 (FDD/TDD) and LTE-A assumptions which have a bearing on the UL control channel design.
Combining IFDMA with the sounding reference signal was presented in R1-050816, “Frequency-domain scheduling with SC-FDMA in UL”, 3GPP TSG-RAN Meeting #42, London, UK, 29 Aug.-2 Sep. 2005, Nokia.
Also of interest is R1-061862, “Uplink Non-data-associated Control Signaling”, TSG-RAN WG1 LTE AdHoc, Cannes, France, Jun. 27-30, 2006, Ericsson. FIG. 1 herein reproduces FIG. 2-1 of R1-061862 and shows the principle of how distributed and localized transmissions are time multiplexed within one UL TTI. The distributed part is transmitted at the beginning of the TTI, and contains at least one pilot block. The first long block in the uplink frame structure is split into two short blocks. The first short block is used for ACK/NACK transmission, where different UEs are separated in the frequency domain by using different “combs”. Which “comb” to use is given by the downlink scheduling assignment. The second short block in is used for reference signals for coherent demodulation of the ACK/NACK and for channel sounding.
A question that has not been adequately addressed thus far relates to the backward compatibility issue of LTE-A with Rel. 8, that is, how to optimize the control channel transmission in such a manner that backward compatibility with LTE terminals operating in the same physical resource can be maintained.